First principles electron-correlated calculations of optical absorption in magnesium clusters

TL;DR

This study uses advanced configuration interaction methods to accurately compute the optical absorption spectra of magnesium clusters, providing benchmark data that aligns well with experimental results and enhances understanding of their electronic properties.

Contribution

The paper presents large-scale CI calculations of magnesium clusters' optical spectra, incorporating electron correlation effects with high accuracy, which is a significant advancement over previous approximate methods.

Findings

Calculated spectra agree with experimental data for Mg2

Electron correlation effects are crucial for accurate optical properties

Results serve as benchmarks for future theoretical and experimental studies

Abstract

In this paper, we report large-scale configuration interaction (CI) calculations of linear optical absorption spectra of various isomers of magnesium clusters Mg$_{n}$ (n=2--5), corresponding to valence transitions. Geometry optimization of several low-lying isomers of each cluster was carried out using coupled-cluster singles doubles (CCSD) approach, and these geometries were subsequently employed to perform ground and excited state calculations using either the full-CI (FCI) or the multi-reference singles-doubles configuration interaction (MRSDCI) approach, within the frozen-core approximation. Our calculated photoabsorption spectrum of magnesium dimer (Mg$_{2}$) isomer is in excellent agreement with the experiments both for peak positions, and intensities. Owing to the sufficiently inclusive electron-correlation effects, these results can serve as benchmarks against which future experiments, as well as calculations performed using other theoretical approaches, can be tested.